Stabilized polyamide compositions containing a copper compound and a lead compound



United States Patent Ofifice 3,340,227 Patented Sept. 5, 1967 3,340,227 STABILIZED POLYAMIDE COMPOSITIONS CON- TAINING A COPPER COMPOUND AND A LEAD COMPOUND Alex Krieger, Emmenbrucke, Switzerland, assignor to Societe de la Viscose Suisse, Emmenbrucke, Switzerland, a corporation of Switzerland No Drawing. Filed July 1, 1965, Ser. No. 468,979 Claims priority, application Switzerland, July 17, 1964, 9,378/ 64 7 Claims. (Cl. 26045.75)

This invention relates to synthetic polyamide compositions which are stabilized against degradation under the influence of heat and light, and to articles made from such compositions, especially textile filaments, fibers, and yarns.

It is known that synthetic polyamides sufier a deterioration of their mechanical properties under the influence of heat and light. When such polyamides are exposed for some time to higher temperatures or to radiation, especially radiation containing ultraviolet rays, they usually become brittle, and their tensile strength decreases considerably. Parallel to this mechanical degradation, the polyamides show a decrease of their viscosity indicating a reduction of their average molecular weight. Since shaped articles, especially textile filaments and yarns, made from polyamides are widely used because of their excellent mechanical properties, the heatand light-sensitivity of such articles is a great disadvantage, and many efforts have been made to prepare synthetic polyamides which retain their strength after exposure to higher temperatures or to light.

A great variety of substances have been proposed as stabilizers for polyamides, and among them also several metal 7 compounds. Thus, German Patent No. 883,644 describes the use of copper salts; German Patent No. 1,111,376 mentions cerium (III) and titanium (III) salts; United States Patent No. 3,067,168 suggests ionic tin salts; and British Patent No. 899,896 proposes tetravalent organic tin compounds. British Patent No. 862,577 describes polyphosphates of cobalt, nickel, copper and manganese; United States Patent No. 2,887,462 recommends manganese salts with a reducing anion; and British Patent No. 935,796 suggests silicates of aluminum, magnesium, and lead.

It has also often been tried to increase the stabilizing effect by using a combination of ditferent substances and also to obtain a protection which is equally effective against heat and light. Thus, French Patent No. 1,099,407 recommends a combination of copper and manganese; and Belgian Patent No. 625,367 uses as stabilizers cuprous chloride or stannous chloride in combination with alkylor arylphosphinates.

When using as stabilizers copper or copper compounds, the polyamides often show a yellow to red discoloration, which is especially unpleasant, when colorless or white textile fibers are to be produced. Furthermore, in the manufacture of copper-stabilized polyamides, it often happens that copper is deposited in the polycondensation installations, and, when melt-spinning polyamide fibers, such deposits may block the spinning filters and interrupt the spinning process. A consequence of such precipitation of copper is, of course, a reduction of the copper content of the polyamide whereby the stabilization effect is diminished.

These difliculties in using copper as stabilizer increase, when it is necessary to prepare polyamide compositions which contain stabilizers in concentrated form. Such concentrates are required in continuous polycondensation processes, where it is usual to mix a major proportion of a basic unstabilized polyamide with a small quantity of the required type of concentrate containing the desired additives, such as stabilizers, pigments, dyes, optical brighteners, etc. The concentrate and the basic polyamide are usually mixed in proportions between 1 to 10 and 1 to 20, and it follows that the concentrate must contain 10 to 20 times the quantity of additives that are desired in the final product.

It is an object of this invention to provide polyamide compositions which are stabilized against degradation under the influence of heat and light.

Another object is to provide stabilized polyamide compositions which are not discolored.

A further object is to provide polyamide compositions containing stabilizers in a concentrated form which, when mixed with a major proportion of unstabilized polyamides yield undiscolored heatand light-stabilized polyamide compositions.

These and other objects are accomplished by the present invention which provides polyamide compositions stabilized against degradation by heat and light by the incorporation with the polyamide during manufacture of copper or a copper compound and a lead compound.

The copper may be derived from any source. Thus, both elemental copper and any suitable inorganic or organic copper compound can be used, for example, oxides, chlorides, bromides, iodides, borates, phosphates, acetates, oxalates, butyrates,'lactates, stearates, benzoates, salicylates, phthalates, or naphthenates of copper. The copper may be in the cuprous or cupric state.

The lead compound should be selected from the colorless lead (II) salts of inorganic or organic acids, for example, the chloride, bromide, sulphate, phosphate, borate, carbonate, formate, acetate, oxalate, citrate, laurate, stearate. In particular, lead (II) acetate is most frequently employed.

To make polymers for direct use, the stabilizers are preferably used in quantities corresponding to between 20 and parts by weight of copper and between 20 and 100 parts by weight of lead, per million parts of polyamide. For concentrates however which are to be mixed with a basic unstabilized polyamide,the quantities of stabilizers used may correspond to between 100 and 1,000 parts by weight of copper and between 100 and 1,000 parts by weight of lead, per million parts of polyamide, according to the intended mixing proportions. If desired, other known stabilizers, for example phenolic antioxidants or phosphor-us oxyacids, can be added.

The stabilizing effect of the combination according to this invention surpasses considerably the effect which can be obtained by use of copper salts alone or of lead salts alone, and especially surprising is the almost equally high protection against degradation by heat and light. To give an example, the tensile strength of yarns made from polycaprolactam and containing as stabilizers copper acetate and lead (11) acetate, which were heated in air during 8 hours to 177 C. or irradiated during 220 hours in a fadeometer, respectively, difiered only to 2-8 percent from the tensile strength of untreated yarns. Yarns made for comparison and containing as stabilizer copper acetate only or lead (II) acetate only had lost by heating 12 percent and 30 percent, and by irradiation 25 percent and 35 percent, respectively, of their original strength. Another comparison yarn containing as stabilizer manganous oxalate, which is preferably used for protection against light, had lost 15 percent of its strength in the irradiation test.

The present invention is generally applicable to polyamides prepared from polyamide precursors, such as .polymerizable mono-amino-carboxylic acids or their amide-forming derivatives, or from suitable diamines and suitable dicarboxylic acids or amide-forming derivatives 3 of these compounds. Preparation and use of such polyamides are described in US. Patents Nos. 2,071,250; 2,071,253; and 2,130,948. The polyamides have recurring carbonamide groups in the main polymer chain separated before polycondensation, while such addition is not necessary when making polymer concentrates.

The invention is illustrated by the following examples in which the incorporation of the stabilizers and the polyby hydrocarbon groups containing at least two carbon 5 condensation schedule was as described above. The color atoms. of spun yarns is given according to visual observation.

There isv a special advantage when using the invention The reduced viscosity (1 is calculated according to for polyamides made from w-amino carboxylic acids, such the formula: as polycaprolactam, poly(w-amino undecanoic acid), In poly(w-amino enanthic acid), poly(w-amino-caprylic 10 (1 acid), poly(w-amino lauric acid), and poly(w-amino tridecyclic a id), wherein the relative viscosity is determined in a While polyamides stabilized according to the invention h n c ntaining 0.2 g. of polyamide fiber in 100 ml. and made by polycondensation of di mines and diof 94% sulfuric acid at a temperature of 20 C. The tencarboxylic acids, e.g., polyhexamethylene adipamide, polysile strength, expressed in grams P denier, is measured hexamethylene suberamide, polyhexamethylene sebacama 11 an the irradiation t st is Carried ut With an ide, polyoctamethylene adipamide, polydodecamethylene Atlas Fadeometer, Typ FD R, made by Atlas Electric lauramide, or poly-m-Xylylene sebacamide, also possess Devices g U-S'A' according to a method the high protection against heat and light mentioned described in the Technical Manual of the American Asabove, they usually show the same reddish discoloration sociation of Textile Chemists and Colorists, published as polyamides stabilized by the use of copper alone. Howby Howes Publishing Co., New York, 1957. ever, poly(wamino carboxylic acids) stabilized according Example I, to the invention, are colorless.

Stabilized poly(w-amino carboxylic acid) compositions Six Polyamide compositions are P p as desofihed containing, as mentioned above, 10 to 20 times the quanabove, five mp itions (1) t0 (5) being made from 5 kg. tity of stabilizers that are desired in the final product, are oapl'oleotam each: and one Composition being made usually somewhat yellowish, but the color disappears when from 5 hexamethylelle diamine p the terms the concentrates are mixed with the required quantity of P C11, P M11, of P meaning Parts y unstabilized basic polymer, and fibers and other articles Weight of pp manganese, of lead, respectively, p f ed from h mixture are 1 -1 million parts of polyamide. Composition (1) contains no The stabilizers are incorporated into the polyamid stabilizer, composition contains of pp r during their manufacture, preferably before or during acetate Parts Composition contains gpolycondensation. The conditions for the polycondensaof maflganous oxalate Parts Composition tion are conventional. When making polyhexamethylene Contains of lead aoetate Parts adipamide, the required copper and lead compounds are Composition (Syoontaios of pp acetate 7 mixed with a 50 percent aqueous solution of hexamethyl- Parts and of lead acetate Parts ene diamine adipate. The solution is warmed until it has and eompositioh contains PP aeetate a concentration of 75-80 percent, and then heated in an Parts and of lead acetate autoclave under nitrogen, until a pressure of 18 atmos- Parts pheres is reached. The pressure is maintained until water 40 v From each Composition yarns are melt p and Coldis evaporated, and then gradually released within 90 mindrawn, each Y having a total of 70 denier utes. Finally, polycondensation is continued under nitroand comprising filaments The y from compositions gen of atmospheric pressure during 30 minutes at about and are colorless, and the y from 277:: compositions (2) and (6) are reddish. Each yarn is ex- To make stabilized polyycaprolactam, caprol t i amined as to: (a) reduced viscosity and tensile strength, melted at about 90 C., and about 1 percent by weight when untreated, reduced Viscosity and tensile strength, of water i added nde stirring o t i i th copper d after having been heated in air during 8 hours at 177 C., lead compounds. The mixture is heated under nitrogen and tensile strength, after having been irradiated during 2 hours at 250 C. in an autoclave. Then the presduring 220 hOllIs in a fadeometer- Ten t s s each are sure is released within 10 minutes, and polycondensation made of each Y according to and and continued under nitrogen during 4 hours at the same tem- Table I shows the averages of these tests indicating perature. The polymer is extruded as usual, washed durin the reduced viscosity and tensile strength of the untreated 24 hours with water of 70 C. to extract the monomers, Y the changes Viscosity and strength of the and finally dried during 3 days at 70 0. under reduced heated yarns expressed i percent of the viscosity and pressure. strength of the untreated yarns, and (c) the change of When making polymers for direct use, 0.1 percent by strength of the irradiated yarns expressed in percent of weight of benzoic acid are also added as chain terminator the strength of e ntreated yarns.

TABLE I (e) Yarns (a) Untreated yarns (b) Yarns heated 8 hours irradiated to 177 C. 220 hrs. in

fadeometer Stabilizer used Reduced Tensile Change ofviscosity, strength,

a Per Reduced Tensile Tensile 0. 2 emer v1scos1ty, strength, strength) percent percent percent (1) 1. 14 5. 2 -57 53 -47 (2) Oopperacetate 1.12 5.1 11 12 25 (3) Manganonsoxalate 1.19 4.2 61 58 15 (4) Lead (II) acetate 1.24 5.3 28 30 -35 (5) Copper acetate lead (11) acetate- 1.17 5.6 +3 +2 -8 (e) do 1.06 4. 3 -2 -2 1 Against untreated yarns.

Example II Two concentrate polyamide compositions are prepared as described above, each made from 5 kg. of caprolactam, but with different stabilizers, the terms parts lead (11) chloride, lead (II) bromide, lead (11) sulfate, lead (H) phosphate, lead (H) borate, lead (II) carbonate, lead (H) for-mate, lead (II) acetate, lead (II) oxalate, lead (II) citrate, lead (II) laurate, and lead (II) stearate,

Cu are parts Pb meaning parts by weight of copper 5 per million parts by weight of the polyamide. or lead, respectively, per million parts of polyamide. 2. A composition in accordance with claim 1 in which Composition (7) contains 11.8 g. of copper acetate the polyamide is a poly(w-'amino carboxylic acid). (=750 parts Cu) and composition (8) contains 11.8 g. 3. A composition in accordance with claim 1 in which of copper acetate 750 parts Cu) and 7.6 g. of lead the polyamide is polycaprolactam. (H) acetate (=825 parts Pb). Composition (7) is red, 10 4. A composition in accordance with claim 1 in which and composition (8) is dark yellow. the polyamide is poly(w-amino undecanoic acid).

5 kg. each of compositions (7) and (8) are mixed with 5. A composition in accordance with claim 1 in which 75 kg. each of a basic polycaprolactam containing no the lead salt is lead (II) acetate. stabilizers except 0.1 percent by Weight of benzoic acid 6. A polyamide composition which is stabilized against as chain terminator. From each of the two mixtures yarns degradation by heat and light comprising a polyamide are melt-spun and cold-drawn, each yarn having a total having recurring carbonamide groups in the main polyof 70 denier (=8 tex.) and comprising 23 filaments. The mer chain separated by hydrocarbon groups containing at yarn from the mixture with composition (7) is pink, and least two carbon atoms, and from 2-0 to 100 parts by the yarn from the mixture with composition (8) is color- Weight of copper derived from the group consisting of less. Each yarn is examined as to: (a) reduced viscosity elemental copper, cuprous oxide, cupric oxide, cuprous and tensile strength, when untreated, (b) reduced vischloride, cupric chloride, cuprous bromide, cupric brocosity and tensile strength, after having been heated in mide, cuprous iodide, cupric iodide, cuprous borate, cuair during 8 hours at 177 C., and (c) tensile strength, p-ric'borate, cuprous phosphate, cupric phosphate, cuprous after having been irradiated during 220 hours in a fadeomacetate, cupric acetate, cuprous oxalate, cupric oxalate, eter. Ten tests each are made of each yarn according to 25 cuprous butyrate, cupric butyrate, cuprous lactate, cupric (a), (b), and (c), and Table II shows the averages of lactate, cuprous stearate, cupric stearate, cuprous benzothese tests indicating (a) the reduced viscosity and tenate, cupric benzoate, cuprous salicylate, cupric salicylate, sile strength of the untreated yarns, (b) the changes of cuprous phthalate, cupric phthalate, cuprous naphthenate, viscosity and strength of the heated yarns expressed in and cupric naphthenate, and between 20 and 100 parts percent of the viscosity and strength of the untreated by Weight of lead derived from the group consisting of yarns, and (c) the change of strength of the irradiated lead (11) chloride, lead (II) bromide, lead (11) sulfate, yarns expressed in percent of the strength of the unlead (II) phosphate, lead (II) borate, lead '(II) carbonate, treated yarns. lead (11) formate, lead (II) acetate, lead (II) oxalate,

TABLE II (a) Untreated yarns (b) Yarns heated 8 hours i a t e d to 177 C. 220 hrs. in Mixing fadeometer proportion, Stabilizer used concentrate/ basic polymer Reduced Tensile Change ofviscosity, strength,

&2 a per Reduced Tensile Tensile 0. 2 9111 viscos1ty, strength, strength,

percent percent percent (7) Copperacetate 1:15 1.22 4.3 -22 2 31 (8) Copper acetate +1ead (II) acetate 1:15 1.08 4. 8 +1 +2 1 Against untreated yarns.

The present invention may be embodied in other spelead (11) citrate, lead (II) laurate, and lead (II) stearate, cific forms without departing from the spirit or essential per million parts by weight of the polyamide. attributes thereof and, accordingly, reference should be 7. A polyamide composition which is stabilized against made to the appended claims, rather than to the foredegradation by heat and light comprising a polyamide going specification as indicating the scope of the invenhaving recurring carbonamide groups in the main polytio mer chain separated by hydrocarbon groups containing at I claim: least two carbon atoms, and from 100 to 1000 parts by 1. A polyamide composition which is stabilized against Weight of pp derived from the 8 P Consisting of degradation by heat and light comprising a polyamide elemental PP cuprous OXide, cupric OXide, 0111310115 having recurring carbonamide groups in the main P01y 6O chloride, cupric chloride, cuprous bromide, cupric bromer chain separated by hydrocarbon groups containing at l cuprous iodide cupric iodide, cupr 0115 borate, least two carbon atoms, and from 20 to 1000 parts by PIlCbOI'EltC, cuprous phosphate, cupric phosphate, cuprous Weight of copper derived from the group (Consisting of acetate, cupric acetate, cuprous oxalate, cupric oxalate, elemental copper, cuprous oxide, cupric Oxide, cuprous cuprous butyrate, cupric butyrate, cuprous lactate, cupric chloride, cupric chloride cuprous bromide cupric lactate, cuprous stearate, cupric stearate, cuprous benzomide, cuprous iodide, cupric iodide, cuprous borate, cupric cupnc i culprous sahcyla'te cupric salicylate, borate, cuprous p p cupric p p cuprous ace cugrous pht alate, cupric phthalate, cuprous naphthenate, tate, cupric acetate, cuprous oxalate cupric oxalate cuan clipnc naphthenat? and between 100 and 1000. pans by Weight of lead denved from the group consistlng of prous butyrate, cupric butyrate, cuprous lactate, cupric lead (H) Chloride lead (11) br I d H lactate stearate, cuPric stearate, cuprous benzolead (II) Phosphate lead (11) b022 2 Iea (II sbulfate a-te, cupric benzoate, cuprous salicylate, cupric salicylate, lead (II) formate lead (II) acetate lead II l i cuprous phthalate, cupric phthalate, cuprous naphthenate, lead (II) citrate, lad (H) laurate, and lead (II) 5:23; and cupric naphthenate, and between 20 and 1000 parts per million parts by Weight of the polyamide. -by weight of lead derived from the group consisting of (R f on following page) 7 8* References Cited DONALD E. CZAJA, Pfiinary Examiner. UNITED STATES PATENTS LEON J. BERCOVITZ, Exdml'nr. 2, 8/1958 s 26045-75 v. P. HOKE, G. W. RAUCHFUS S, 111., 2,919,258 12/ 1959 'Pietrusza et a1 26045.75 5 Assistant Examiners 3,066,034 11/1962 Temin 26045.75

FOREIGN PATENTS 906,893 6/1945 France.

5,350 9/1954 Germany. 

1. A POLYAMIDE COMPOSITION WHICH IS STABILIZED AGAINST DEGRADATION BY HEAT AND LIGHT COMPRISING A POLYAMIDE HAVING RECURRING CARBONAMIDE GROUPS IN THE MAIN POLYMER CHAIN SEPARATED BY HYDROCARBON GROUPS CONTAINING AT LEAST TWO CARBON ATOMS, AND FROM 20 TO 1000 PARTS BY WEIGHT OF COPPER DERIVED FROM THE GROUP CONSISTING OF ELEMENTAL COPPER, CUPROUS OXIDE, CUPRIC OXIDE, CUPROUS CHLORIDE, CUPRIC CHLORIDE, CUPROUS BROMIDE, CUPRIC BROMIDE, CUPROUS IODIDE, CUPRIC IODIDE, CUPROUS BORATE, CUPRIC BORATE, CUPROUS PHOSPHATE, CUPRIC PHOSPHATE, CUPROUS ACETATE, CUPRIC ACETATE, CUPROUS OXALATE, CUPRIC OXALATE, CUPROUS BUTYRATE, CUPRIC BUTYRATE, CUPROUS LACTATE, CUPRIC LACTATE, CUPROUS STEARATE, CUPRIC STEARATE, CUPROUS BENZOATE, CUPRIC BENZOATE, CUPROUS SALICYLATE, CUPRIC SALICYLATE, CUPROUS PHTHALATE, CUPRIC PHTHALATE, CUPROUS NAPHTHENATE, AND CUPRIC NAPHTHENATE, AND BETWEEN 20 AND 1000 PARTS BY WEIGHT OF LEAD DERIVED FROM THE GROUP CONSISTING OF LEAD (II) CHLORIDE, LEAD (II) BROMIDE, LEAD (II) SULFATE, LEAD (II) PHOSPHATE, LEAD (II) BORATE, LEAD (II) CARBONATE, LEAD (II) FORMATE, LEAD (II) ACETATE, LEAD (II) OXALATE, LEAD (II) CITRATE, LEAD (II) LAURATE, AND LEAD (II) STEARATE, PER MILLION PARTS BY WEIGHT OF THE POLYAMIDE. 